I suspect they're using resolutions higher than 1920 x 1080. 1920 x 1080 isn't really considered "high res" these days. The native res on my
monitor, for example, is 2560 x 1440. Many laptops (MS Surface Pros, for
example) are running at similar, higher resolutions.
Regardless,
the problem isn't really the monitor's resolution. It's the fact that these high
resolutions force people to change the DPI setting for their monitor,
running at 125% scaling, 150%, etc., instead of 100%. This forces everything to
appear larger on the screen, but often introduces scaling issues with
apps that aren't DPI aware.
There are some
settings you can play with, at least on Windows 10, to see if that fixes
display issues with MLO. Find the mlo.exe, right-click on it, Properties,
Compatibility tab, "Change high DPI settings" button (near the bottom), try the different "High DPI scaling override" options.